Protein rotational mobility and lipid fluidity of purified and reconstituted cytochrome c oxidase.

摘要: The rotational mobility of spin-labeled bovine heart mitochondrial cytochrome c oxidase in purified form, and incorporated into lipid vesicles was studied. A rigidly attached short chain maleimide spin label permitted by saturation transfer electron paramagnetic resonance. long used to detect the fluidity hydrocarbon region adjacent protein conventional EPR. One method preparing enzyme resulted a high degree at 4/sup 0/C both detergent-solubilized (effective correlation time 100 ns) reconstituted membranes (correlation 40 ..mu..s). By contrast, another purification procedure little or no submillisecond form membranes, suggesting presence large aggregates. Thus, state aggregation appears depend on prior reconstitution. mobile immobile enzymes had same activity. In preparations, bulk quite fluid 0/C, as probed free fatty acid label. protein, more » label, also containing enzyme,but strongly immobilized enzyme. strong immobilization our preparations is apparently caused protein-protein interactions, not rigidity protein-lipid boundary. « less